Dual rotating electromagnetic unit



Sept. 10, 1957 D. F. SHELDON DUAL ROTATING ELECTROMAGNETIC UNIT Filed Oct.

INVENTORK DONALD F. SHELDON ATTORNEY United States Patent DUAL ROTATING ELECTROMAGNETIC UNIT Donald F. Sheldon, Minneapolis, Minn, assignor to Mirineapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application October 5, 1954, Serial No. 460,415

7 Claims. (Cl. 310-113) This invention pertains to rotating electromagnetic apparatus such as motors, generators and the like and is directed especially to the pancake type of rotative electro magnetic device wherein it is desired to have a low axial length to diameter ratio. A combination motorspeed responsive generator is shown and described and is characterized by having a very low axial length in comparison to prior art motor-speed responsive generator units.

An object of this invention is to provide an improved type of pancake type rotative electromagnetic apparatus.

Another object of this invention is to provide an improved motor-speed responsive generator unit.

A further object is to provide an improved combination motor-speed responsive generator unit wherein the device is characterized by having a low axial length to diameter ratio.

Other and more specific objects of the invention, including constructional details and the operation of rotative electromagnetic apparatus embodying my invention, will be set forth more fully and become apparent from a reading of the following specification and appended claims, in conjunction with the accompanying drawing in which:

Figure 1 is a transverse cross-sectional view of a combination motor-speed responsive generator incorporating the teaching of the invention;

Figure 2 is an axial cross-sectional view of the apparatus shown in Figure 1; and

Figure 3 is a plan View of a lamination used in the stator of the device shown in Figures 1 and 2, on a smaller scale.

In Figures 1 and 2 is shown a housing or base member for the combination motor-speed responsive generator unit. Housing 10, which may be of a magnetic material, is shown to be a cup-like member having a tubular main section closed oil? at one end as at 12 and open at the other end. The open end of housing 10 is recessed as at 14 so as to provide a suitable shoulder against which is positioned an end plate 16, end plate 16 being held, in position with respect to housing 10 by means of a suitable snap ring 18 disposed in a suitable recess 20 in housing 10.

Stationarily supported within housing 10 by suitable stud means 22 is a stator member for the combination motor-speed responsive generator generally identified by reference numeral 24. Stator member 24 comprises a plurality of identical laminations 26, shown in detail in Figure 3, arranged flatwise in register with one another. Referring to Figure 3, it is seen that each lamination 26 comprises a circular yoke portion 28 from which depend inwardly and outwardly extending pole portions 30 and 32 respectively. Inwardly extending pole pieces 39 have concave pole faces 34 thereon and the outwardly extending pole members 32 have convex pole faces 36 thereon.

A magnetic inner-pole member 38 is positioned concentrically with respect to the pole faces 34 of the inwardly extending poles 30 of the stator member 24 and define therewith a first annular air gap 40. Magnetic inner-pole 38 has an end portion of reduced diameter extending through a suitable central aperture 42 in end Patented Sept. 10, 1957 portion 12 of housing 10 and the outer extremity of the reduced portion is threaded as at 44 so as to cooperate with a lock nut 46. The threaded end of inner-pole member 38 is provided with a tool receiving recess 48 so as to provide a means of rotating the inner-pole with respect to the housing, the purpose of which will become clearer as the description proceeds.

The outwardly extending poles 32 with their pole faces 36 thereon are adapted to be concentric with the tubular portion of housing member 10 so as to define therewith a second annular air gap 50 concentric with the first air gap 49. A plurality of windings 52 are positioned on the outwardly extending pole members 32 and are energized from a suitable polyphase or split phase alternating current source so as to develop a rotating magnetic field between the pole faces 36 and the magnetic housing 10.

Winding means 54, adapted to be energized by alternating current from a suitable source, not shown, are positioned on alternate ones of the inwardly extending pole members 30. Signal or sensing windings 56 are positioned on the other of the inwardly extending pole members 30 and are adapted to be connected to suitable control means or circuitry, not shown. Thus windings 54 may be considered as the primary windings on a speed responsive generator unit while windings 56 may be considered the secondary windings. As seen in Figure 1, inner-pole member 38 has a fiatted portion 53 thereon which gives the inner-pole member a magnetic asymmetry. Thus, as will be well understood by those skilled in the art, the inner-pole member 38 may be rotated by a slacking off of jam nut 46 with respect to the threaded portion 44 and then tuning the inner-pole 38 to that position which produces the minimum zero speed signal from the speed responsive generator unit. While a flatted inner-pole is shown, it will be appreciated that other methods of reducing the residual or zero speed signal may be employed without departing from the spirit and the scope of the invention. A bearing unit 60 is positioned in a suitable recess 62 in the inwardly extending end of inner-pole member 38. Another bearing member 64 is positioned in a suitable central aperture 66 of end plate 16 of housing 10 and is adapted to be concentric with bearing 60. Bearings 60 and 64 serve to journal a rotor shaft 68, the inner end of which terminates in re cess 62 of inner-pole member 38 and the outer end of which would be adapted to be connected to suitable control means, not shown, while the intermediate portion of the rotor shaft 68 serves to support a double cup rotor member 76, made out of a suitable conductive material such as copper, aluminum or the like. Rotor member 70 has a radial portion 72 disposed parallel to stator member 24 from which depend two axial cup-like portions 74 and 76 disposed respectively in the concentric first and second annular air gaps 40 and 50. Fortion 76 of rotor member 70 cooperates with the rotating magnetic flux developed in the second annular air gap so as to become the driven part of a motor and thus cause rotor shaft 68 to rotate. Since portion 74 of the rotor is integral with portion 76, the rotation developed by portion 76 is imparted to portion 74. Portion 74 of rotor member 79 thus becomes the driven part of a speed responsive generator including the inwardly extending pole portions 3% of stator 24 upon which are disposed the primary and secondary windings 54 and 56 respectively together with the adjustable inner-pole member 38. As will be well understood by those skilled in the art, when rotor member 70 is at a standstill, no signal will be developed the secondary windin as 56 of the speed responsive generator unit. When rotor member 70 is rotating by virtue of the motor portion of the apparatus, a signal will be developed in the secondary windings 56 proportional to the speed of rotation thereof.

'It will be appreciated that the unique device described above has the advantage of being inexpensive to manufacture inasmuch as it uses a one piece stator as well as a one piece rotor and is further characterized by having a very low axial length with respect to the diameter of the device, this being advantageous in applications wherein a very small axial space is allowed for a motor and a speed responsive generator.

While I have shown and described a specific embodiment of this invention, further modifications and improvements will occur to those skilled in the art. I desire to be understood, therefore, that this invention is not limited to the particular form shown and I intend in appended claims to cover all modifications which do not depart from the spirit and the scope of this invention.

What I claim is:

p 1. In apparatus of the class described comprising a base, a magnetic core structure on said base having a closed yoke portion with a plurality of inwardly and outwardly extending pole portions thereon, a magnetic member on said base and positioned with respect to said inwardly extending pole portions so as to define with pole faces thereon a first air gap, an extension of said base adjacent to said outwardly extending pole portions so as to define with'pole faces thereon a second air gap, winding means disposed on said outwardly extending pole portions and adapted to be energized by alternating current voltage means so as to develop a rotating flux field in said second air gap, primary winding means positioned on alternate ones of said inwardly extending pole portions and adapted to be energized by alternating current voltage means, secondary winding means positioned on the other of said inwardly extending pole portions, and a rotor member having two portions ofconductive material disposed in said air gaps.

2. In apparatus of the class described comprising a magnetic core structure having a circular yoke portion with a plurality of inwardly and outwardly radially extending pole portions thereon, winding means disposed on some of said pole portions and adapted to be energized by alternating current voltage means so as to develop a rotating fiux field, primary winding means positioned on alternate ones of the other of said pole portions and adapted to be energized by alternating current voltage means, secondary winding means positioned on the other of said pole portions, and a rotor member having portions of conductive material positioned adjacent pole faces on said pole portions.

3. In apparatus of the class described comprising a housing, a laminated core structure mounted within said housing and having a circular yoke portion with a plurality of inwardly and outwardly radially extending pole por tions thereon, a magnetic inner-pole member mounted on said housing and concentrically positioned adjacent to said inwardly extending pole portions so as to define with pole faces thereon a first annular air gap, an axial magnetic extension of said housing concentric with said outwardly extending pole portions so as to define with pole faces thereon a second annular air gap, winding means disposed on said outwardly extending pole portions and adapted to be energized by alternating current voltage means so as to develop a rotating flux field in said second air gap, primary winding means positioned on some of said inwardly extending pole portions and adapted to be energized by voltage means, secondary winding means positioned on the other of said inwardly extending pole portions, and a rotor member mounted for rotation on said magnetic member and said base and having two concentric axial portions of conductive material disposed in said air gaps.

4. In apparatus of the 'class described comprising a housing member having a pair of end portions; a stator member positioned within said housing, said stator comprising a yoke portion and a plurality of pole portions, some of said pole portions extending toward a portion of said housing member and having pole faces defining therewith a first air gap, and the other pole portions extending toward another portion of said housing and having pole faces defining therewith a second air gap; winding means on said first air gap defining pole portions energized to develop a rotating magnetic flux field in said first air gap; energized winding means on alternate ones of said other pole portions and signal sensing winding means on the other of said other pole portions; and a rotor member having portions disposed in said first and second air gaps the rotor portion in said first of said air gaps coacting with said rotating'fiux field so as to serve as a motor rotor and the rotor portion in said second of said air gaps serving as a speed responsive generator rotor.

S. In rotating electromagnetic apparatus of the class described comprising a housing member, a stator member positioned within said housing, said stator comprising a yoke portion and a plurality of radial pole portions, some of said pole portions extending toward a magnetic portion of said housing member and having pole faces defining therewith a first axial air gap, and the other poie portions extending toward another magnetic portion of said housing and having pole faces defining therewith a second axial air gap; winding means on said pole portions; and a rotor member having portions disposed in said first and second air gaps.

6. A combination motor-speed responsive generator characterized by having a low axial length to diameter ratio comprising a stator member having a circular yoke portion with integral inwardly and outwardly radially extending pole portions thereon; winding means on said stator energized so as to develop a rotating magnetic flux field about the extremities of said outwardly extending poie portions, energizing and sensing winding means disposed on said inwardly extending pole portions; and a rotor member rotatably supported adjacent said stator and having a pair of concentric conductive cup portions, one of said cup portions being disposed adjacent to said extremities of said outwardly extending pole portions and coacting with said rotating magnetic flux field so as to rotate said rotor member and the other of said cup portions being disposed adjacent the innerrextrernities of said inwardly extending pole portions and coactingwith a liux developed by said energizing winding means so as to develop a rotor speed responsive signal in saidsensing winding means.

7. A rotative electromagnetic device of the class described characterized by having a low axial length to diameter ratio comprising a stator member having a circular yoke portion with integral inwardly and outwardly radially extending pole portion thereon; winding means on said stator; and a rotor member rotatably supported and having a pair of concentric conductive cup portions, one of said cup portions being disposed adjacent tothe outer extremities of said outwardly extending pole portions and the other of said cup portions being disposed adjacent the inner extremitie of said inwardly extending pole portions.

References Cited in the file of this patent UNITED STATES PATENTS 859,369 Collins July 9, 1907 912,144 Mavor Feb. 9, 1909 1,094,389 Howe Apr. 21, 1914 1,196,713 Nelson Aug. 20, 1916 1,275,665 Eichbaum Aug. 13, 1918 1,562,263 Sommer Nov. 17, 1925 1,595,550 Howard Aug. 10, 1926 2,206,920 Riggs July 9, 1940' FOREIGN PATENTS 282,876 GreatBritain Dec. 28,-1927 418,659 Great Britain Jan. 28, 1934 330,837 Italy Oct. 24, 1935 

